Williams syndrome

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

Synonyms and keywords: Beuren-Williams syndrome; supravalvular aortic stenosis hypercalcemia syndrome; Williams syndrome; Williams-Beuren syndrome; Chromosome 7q11.23 deletion syndrome, 1.5- to 1.8-mb; WMS; WS

Overview

Williams syndrome (also Williams-Beuren syndrome) is a rare genetic disorder characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers, coupled with unpredictably occurring negative outbursts; mental retardation coupled with unusual (for persons who are diagnosed as mentally retarded) language skills; a love for music; and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia.

Historical Perspective

The syndrome was first identified in 1961 by Dr. J. C. P. Williams of New Zealand.

Classification

There is no established system for the classification of Williams syndrome.

Pathophysiology

It is thought that Williams syndrome is caused by deletion of genetic material from the region q11.2 of chromosome 7. The deleted region includes more than 20 genes, and researchers believe that the loss of several of these genes probably contributes to the characteristic features of this disorder. CLIP2, ELN, GTF2I, GTF2IRD1, and LIMK1 are among the genes that are typically deleted in people with Williams syndrome. Researchers have found that loss of the ELN gene, which codes for the protein elastin, is associated with the connective-tissue abnormalities and cardiovascular disease (specifically supravalvular aortic stenosis (SVAS) and supravalvular pulmonary stenosis (SVPS)) found in many people with this syndrome. Studies suggest that deletion of LIMK1, GTF2I, GTF2IRD1, and perhaps other genes may help explain the characteristic difficulties with visual–spatial tasks. Additionally, there is evidence that the loss of several of these genes, including CLIP2, may contribute to the unique behavioral characteristics, mental retardation, and other cognitive difficulties seen in Williams syndrome.

Epidemiology and Demographics

The incidence of Williams syndrome is approximately 1 per 75,000 individuals worldwide. Williams syndrome is considered for about 6% of all genetic cases of developmental disability. William syndrome affects male and female in equal numbers and infants of any race may be affected.

Risk Factors

There are no established risk factors for Williams syndrome.

Screening

There is insufficient evidence to recommend routine screening for Williams syndrome.

Natural History, Complications, and Prognosis

Common complications of Williams syndrome include:

• Cardiovascular disease
• Failure to thrive
• Connective tissue changes
• Endocrine abnormalities

There is no significant reduction in life expectancy in child diagnosed with Williams syndrome unless there is any significant heart condition or problems in kidney.

Diagnosis

The clinical diagnosis of Williams syndrome can be made in early childhood based on characteristic facial features. However, the diagnosis of Williams syndrome is confirmed by genetic testing (fluorescent in situ hybridization) that can detect a deletion of one elastin gene on chromosome 7.

Symptoms

It is characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers, coupled with unpredictably occurring negative outbursts; mental retardation coupled with unusual (for persons who are diagnosed as mentally retarded) language skills; a love for music; and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia.

Williams syndrome shares some features with autism (such as difficulty understanding the state of mind of conversational partners) and Fetal alcohol syndrome (e.g., certain facial features, possible mental retardation, and negative potential outbursts), although persons with Williams generally possess very good social skills, such that this condition is sometimes called "cocktail-party syndrome". There also appears to be a higher prevalence of left-handedness and left-eye dominance in those with Williams, and cases of absolute pitch appear to be significantly higher amongst those with the condition.

Laboratory Findings

Laboratory findings consistent with the diagnosis of Williams syndrome include elevated calcium level with hypercalciuria , mild thyroid-stimulating hormone elevation with normal thyroxine T4 (sub-clinical hypothyroidism in 5 to 10 percent ) , and abnormal glucose tolerance test in 60 to 75 percent.

Electrocardiogram

An ECG may be helpful to look for any cardiac anomalies such as septal defects that may be related to Williams syndrome.

X-ray

There are no x-ray findings associated with Williams syndrome. However, an x-ray may be helpful to look for associated anomalies with Williams syndrome.

Echocardiography or Ultrasound

Renal ultrasound may be helpful in the diagnosis of Williams syndrome. Findings on renal ultrasound suggestive of Williams syndrome include bladder diverticula, ectopic or horseshoe kidney, and renal aplasia or hypoplasia. Nephrocalcinosis secondary to hypercalciuria is detected in approximately 5 to 10 percent of patients undergoing renal ultrasound.

CT scan

There are no CT scan findings associated with Williams syndrome.

MRI

There are no MRI findings associated with Williams syndrome.

Other Imaging Findings

There are no other imaging findings associated with Williams syndrome.

Other Diagnostic Studies

Other diagnostic studies for Williams syndrome include audiologic evaluation, which demonstrates high tone sensorineural hearing loss, and ophthalmic evaluation, which demonstrates strabismus and refractive errors.

Treatment

Based on 2020 American Academy of Pediatrics (AAP) healthcare supervision guidelines for WS, approach to management of Williams syndrome consists of 3 major steps:

• 1. Initial evaluation
• 2. Continued surveillance
• 3. Management of specific conditions

Medical Therapy

There is no treatment for Williams syndrome; the mainstay of therapy is supportive care and management of specific conditions or complications related to Williams syndrome.

Surgery

Surgery is the mainstay of treatment for supra-valvular aortic stenosis, which is one of the specific condition related to Williams syndrome.

Primary Prevention

There are no established measures for the primary prevention of Williams syndrome.

Secondary Prevention

There are no established measures for the secondary prevention of Williams syndrome.

External links

• Williams Syndrome Association